Maybe you can share the address of the page in question, it might help. Also, please add the code of the send button in your page.
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Nitzan TomerApr 18 '12 at 22:12

Okay, I added the other code you mentioned to my question above -- this is the first time I'm using any Facebook plugin so I'm sure I blew it somewhere but I can't see where -- the tags are in the right place and the Facebook debugger successfully finds and parses them.
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wantTheBestApr 18 '12 at 22:29

Well that fixed it. In order to make it work, I had to change the data-href in the button to match the og:url meta tag. Now the Send dialog box appears with all my meta tags showing up (image, url, description, title). Thanks!
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wantTheBestApr 18 '12 at 22:45

@wantTheBest But why data-href and og:url need to be the same? I'm getting a 401 Unauthorized when they are different. But the different URLs can be accessed without problems in any browser.
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felipe.zknJul 18 '14 at 10:53